Cycloheptatriene molybdenum (0) precursors for deposition of molybdenum films

ABSTRACT

Molybdenum(0) coordination complexes comprising at least one cycloheptatriene ligand and optionally one or more neutral ligands which coordinate to the metal center by carbon, nitrogen or phosphorous are described. Methods for depositing molybdenum-containing films on a substrate are described. The substrate is exposed to a molybdenum precursor and a reactant to form the molybdenum-containing film (e.g., elemental molybdenum, molybdenum oxide, molybdenum carbide, molybdenum silicide, molybdenum nitride). The exposures can be sequential or simultaneous.

TECHNICAL FIELD

Embodiments of the disclosure relate to molybdenum precursors andmethods for depositing molybdenum-containing films. More particularly,embodiments of the disclosure are directed to cycloheptatrienemolybdenum(0) precursors and methods of use thereof.

BACKGROUND

The semiconductor processing industry continues to strive for largerproduction yields while increasing the uniformity of layers deposited onsubstrates having larger surface areas. These same factors incombination with new materials also provide higher integration ofcircuits per unit area of the substrate. As circuit integrationincreases, the need for greater uniformity and process control regardinglayer thickness rises. As a result, various technologies have beendeveloped to deposit layers on substrates in a cost-effective manner,while maintaining control over the characteristics of the layer.

Chemical vapor deposition (CVD) is one of the most common depositionprocesses employed for depositing layers on a substrate. CVD is aflux-dependent deposition technique that requires precise control of thesubstrate temperature and the precursors introduced into the processingchamber in order to produce a desired layer of uniform thickness. Theserequirements become more critical as substrate size increases, creatinga need for more complexity in chamber design and gas flow technique tomaintain adequate uniformity.

A variant of CVD that demonstrates excellent step coverage is cyclicaldeposition or atomic layer deposition (ALD). Cyclical deposition isbased upon atomic layer epitaxy (ALE) and employs chemisorptiontechniques to deliver precursor molecules on a substrate surface insequential cycles. The cycle exposes the substrate surface to a firstprecursor, a purge gas, a second precursor and the purge gas. The firstand second precursors react to form a product compound as a film on thesubstrate surface. The cycle is repeated to form the layer to a desiredthickness.

The advancing complexity of advanced microelectronic devices is placingstringent demands on currently used deposition techniques.Unfortunately, there is a limited number of viable chemical precursorsavailable that have the requisite properties of robust thermalstability, high reactivity, and vapor pressure suitable for film growthto occur. In addition, precursors that often meet these requirementsstill suffer from poor long-term stability and lead to thin films thatcontain elevated concentrations of contaminants such as oxygen,nitrogen, and/or halides that are often deleterious to the target filmapplication.

Molybdenum and molybdenum based films have attractive material andconductive properties. These films have been proposed and tested forapplications from front end to back end parts of semiconductor andmicroelectronic devices. Processing a molybdenum precursor ofteninvolves use of halogen and carbonyl-based substituents. These ligandsprovide sufficient stability at the expense of reduced reactivity,increasing process temperature. Other molybdenum precursors includeamide ligands, which can cause nitride impurities. There is, therefore,a need in the art for molybdenum precursors that are free of halogen andcarbonyl groups that react to form molybdenum metal and molybdenum basedfilms.

SUMMARY

One or more embodiments of the disclosure are directed to metalcoordination complexes comprising molybdenum(0), at least onecycloheptatriene ligand and optionally one or more neutral ligand. Eachneutral ligand is coordinated by carbon, nitrogen or phosphorous.

Additional embodiments of the disclosure are directed to a method ofdepositing a film. The method comprises exposing a substrate to amolybdenum(0) precursor comprising at least one cycloheptatriene ligandand optionally one or more neutral ligands. Each neutral ligand iscoordinated by carbon, nitrogen or phosphorous. The substrate is exposedto a reactant to react with molybdenum(0) precursor to form a molybdenumfilm on the substrate.

Further embodiments of the disclosure are directed to a method ofdepositing a film. The method comprises forming a molybdenum-containingfilm in a process cycle comprising sequential exposure of a substrate toa molybdenum(0) precursor, purge gas, reactant, and purge gas. Themolybdenum(0) precursor comprises at least one cycloheptatriene ligandand optionally one or more neutral ligands. Each neutral ligand iscoordinated by carbon, nitrogen or phosphorous.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the disclosurecan be understood in detail, a more particular description of thedisclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of the disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 illustrates a process flow diagram of a method in accordance withone or more embodiments of the disclosure; and

FIGS. 2A-2C illustrate exemplary metal complexes in accordance with oneor more embodiments of the disclosure.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the invention, it isto be understood that the invention is not limited to the details ofconstruction or process steps set forth in the following description.The invention is capable of other embodiments and of being practiced orbeing carried out in various ways.

Embodiments of the disclosure provide precursors and processes fordepositing molybdenum-containing films. The precursor comprises a metalcoordination complex. The metal coordination complexes of one or moreembodiments are substantially free of halogens and carbonyl groups. Themetal coordination complex comprises at least one cycloheptatrieneligand and is used under ALD and CVD conditions. The process of variousembodiments uses vapor deposition techniques, such as an atomic layerdeposition (ALD) or chemical vapor deposition (CVD) to providemolybdenum films. The molybdenum precursors of one or more embodimentsare volatile and thermally stable, and, thus, suitable for vapordeposition.

The molybdenum coordination complexes of one or more embodiments aresubstantially free of halogen and carbonyl groups. As used herein, theterm “substantially free” means that there is less than about 5%,including less than about 4%, less than about 3%, less than about 2%,less than about 1%, and less than about 0.5% of halogen, on an atomicbasis, in the molybdenum coordination complexes. In some embodiments,the molybdenum coordination complexes are substantially free of carbonylgroups, and there is less than about 5%, including less than about 4%,less than about 3%, less than about 2%, less than about 1%, and lessthan about 0.5% of carbonyl group, on an atomic basis, in the molybdenumcoordination complexes.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal and/or bake the substratesurface. In addition to film processing directly on the surface of thesubstrate itself, in the present invention, any of the film processingsteps disclosed may also be performed on an underlayer formed on thesubstrate as disclosed in more detail below, and the term “substratesurface” is intended to include such underlayer as the contextindicates. Thus, for example, where a film/layer or partial film/layerhas been deposited onto a substrate surface, the exposed surface of thenewly deposited film/layer becomes the substrate surface.

According to one or more embodiments, the method uses an atomic layerdeposition (ALD) process. In such embodiments, the substrate surface isexposed to the precursors (or reactive gases) sequentially orsubstantially sequentially. As used herein throughout the specification,“substantially sequentially” means that a majority of the duration of aprecursor exposure does not overlap with the exposure to a co-reagent,although there may be some overlap.

As used in this specification and the appended claims, the terms“precursor”, “reactant”, “reactive gas” and the like are usedinterchangeably to refer to any gaseous species that can react with thesubstrate surface.

“Atomic layer deposition” or “cyclical deposition” as used herein refersto the sequential exposure of two or more reactive compounds to deposita layer of material on a substrate surface. As used in thisspecification and the appended claims, the terms “reactive compound”,“reactive gas”, “reactive species”, “precursor”, “process gas” and thelike are used interchangeably to mean a substance with a species capableof reacting with the substrate surface or material on the substratesurface in a surface reaction (e.g., chemisorption, oxidation,reduction). The substrate, or portion of the substrate is exposedsequentially to the two or more reactive compounds which are introducedinto a reaction zone of a processing chamber. In a time-domain ALDprocess, exposure to each reactive compound is separated by a time delayto allow each compound to adhere and/or react on the substrate surface.In a spatial ALD process, different portions of the substrate surface,or material on the substrate surface, are exposed simultaneously to thetwo or more reactive compounds so that any given point on the substrateis substantially not exposed to more than one reactive compoundsimultaneously. As used in this specification and the appended claims,the term “substantially” used in this respect means, as will beunderstood by those skilled in the art, that there is the possibilitythat a small portion of the substrate may be exposed to multiplereactive gases simultaneously due to diffusion, and that thesimultaneous exposure is unintended.

In one aspect of a time-domain ALD process, a first reactive gas (i.e.,a first precursor or compound A) is pulsed into the reaction zonefollowed by a first time delay. Next, a second precursor or compound Bis pulsed into the reaction zone followed by a second delay. During eachtime delay a purge gas, such as argon, is introduced into the processingchamber to purge the reaction zone or otherwise remove any residualreactive compound or by-products from the reaction zone. Alternatively,the purge gas may flow continuously throughout the deposition process sothat only the purge gas flows during the time delay between pulses ofreactive compounds. The reactive compounds are alternatively pulseduntil a desired film or film thickness is formed on the substratesurface. In either scenario, the ALD process of pulsing compound A,purge gas, compound B and purge gas is a cycle. A cycle can start witheither compound A or compound B and continue the respective order of thecycle until achieving a film with the desired thickness.

In an aspect of a spatial ALD process, a first reactive gas and secondreactive gas (e.g., hydrogen radicals) are delivered simultaneously tothe reaction zone but are separated by an inert gas curtain and/or avacuum curtain. The substrate is moved relative to the gas deliveryapparatus so that any given point on the substrate is exposed to thefirst reactive gas and the second reactive gas.

Without intending to be bound by theory, it is thought that the presenceof halogens, carbonyls groups, and, in some cases, oxygen, in thestructure of molybdenum (Mo) precursors can pose challenges, as halogenand oxygen contamination may affect device performance and hence requireadditional removal procedures. Carbonyl (CO) binds strongly to metals,requiring higher thermal budget, or the use of additional reagents forits removal. Carbonyl (CO) can redeposit and poison other metalsurfaces.

Molybdenum (Mo) can be grown by atomic layer deposition or chemicalvapor deposition for many applications. One or more embodiments of thedisclosure advantageously provide processes for atomic layer depositionor chemical vapor deposition to form molybdenum-containing films. Asused in this specification and the appended claims, the term“molybdenum-containing film” refers to a film that comprises molybdenumatoms and has greater than or equal to about 1 atomic % molybdenum,greater than or equal to about 2 atomic % molybdenum, greater than orequal to about 3 atomic % molybdenum, greater than or equal to about 4atomic % molybdenum, greater than or equal to about 5 atomic %molybdenum, greater than or equal to about 10 atomic % molybdenum,greater than or equal to about 15 atomic % molybdenum, greater than orequal to about 20 atomic % molybdenum, greater than or equal to about 25atomic % molybdenum, greater than or equal to about 30 atomic %molybdenum, greater than or equal to about 35 atomic % molybdenum,greater than or equal to about 40 atomic % molybdenum, greater than orequal to about 45 atomic % molybdenum, greater than or equal to about 50atomic % molybdenum, or greater than or equal to about 60 atomic %molybdenum. In some embodiments, the molybdenum-containing filmcomprises one or more of molybdenum metal (elemental molybdenum),molybdenum oxide (MoO₂, MoO₃), molybdenum carbide (MoC, Mo₂C),molybdenum silicide (MoSi₂), or molybdenum nitride (Mo₂N). The skilledartisan will recognize that the use of molecular formula like MoSi_(x)does not imply a specific stoichiometric relationship between theelements but merely the identity of the major components of the film.For example, MoSi_(x) refers to a film whose major composition comprisesmolybdenum and silicon atoms. In some embodiments, the major compositionof the specified film (i.e., the sum of the atomic percents of thespecified atoms) is greater than or equal to about 95%, 98%, 99% or99.5% of the film, on an atomic basis.

With reference to FIG. 1, one or more embodiments of the disclosure aredirected to method 100 of depositing a film. The method illustrated inFIG. 1 is representative of an atomic layer deposition (ALD) process inwhich the substrate or substrate surface is exposed sequentially to thereactive gases in a manner that prevents or minimizes gas phasereactions of the reactive gases. In some embodiments, the methodcomprises a chemical vapor deposition (CVD) process in which thereactive gases are mixed in the processing chamber to allow gas phasereactions of the reactive gases and deposition of the thin film.

In some embodiments, the method 100 includes a pre-treatment operation105. The pre-treatment can be any suitable pre-treatment known to theskilled artisan. Suitable pre-treatments include, but are not limitedto, pre-heating, cleaning, soaking, native oxide removal, or depositionof an adhesion layer (e.g. titanium nitride (TiN)). In one or moreembodiments, an adhesion layer, such as titanium nitride, is depositedat operation 105. In other embodiments, molybdenum can be integratedwithout the need for an adhesion liner.

At deposition 110, a process is performed to deposit amolybdenum-containing film on the substrate (or substrate surface). Thedeposition process can include one or more operations to form a film onthe substrate. In operation 112, the substrate (or substrate surface) isexposed to a molybdenum precursor to deposit a film on the substrate (orsubstrate surface). The molybdenum precursor can be any suitablemolybdenum-containing compound that can react with (i.e., adsorb orchemisorb onto) the substrate surface to leave a molybdenum-containingspecies on the substrate surface.

Current molybdenum precursors for ALD of metallic films use halogen andcarbonyl-based substituents, which provide sufficient stability at theexpense of reduced reactivity, increasing process temperature. Amideligands can cause nitride impurities. Accordingly, one or moreembodiments use at least one cycloheptatriene ligand and optionally oneor more neutral carbon, nitrogen and phosphorous coordinating ligand.These ligands provide molybdenum precursors with improved thermalstability, while retaining high volatility and producingmolybdenum-containing films with minimum impurities.

Unless otherwise indicated, the term “lower alkyl,” “alkyl,” or “alk” asused herein alone or as part of another group includes both straight andbranched chain hydrocarbons, containing 1 to 20 carbons, 1 to 10carbons, 1 to 6 carbons or 1 to 4 carbons in the normal chain, such asmethyl, ethyl, propyl, isopropyl, butyl, t-butyl, isobutyl, pentyl,hexyl, isohexyl, heptyl, 4,4-dimethylpentyl, octyl,2,2,4-trimethyl-pentyl, nonyl, decyl, undecyl, dodecyl, the variousbranched chain isomers thereof, and the like. Such groups may optionallyinclude up to 1 to 4 substituents. The alkyl may be substituted orunsubstituted.

In one or more embodiments, the molybdenum precursor has a generalformula of Mo(C₇R₈)(L1)_(x)(L2)_(y)(L3), where R is hydrogen, Me-, Et-,iPr-, or tBu-, L1 is one or more monodentate ligand, L2 is one or morebidentate ligand, L3 is a tridentate ligand, and x+2y+3z equals 3. Themonodentate, bidentate and tridentate ligands each coordinate by carbon,nitrogen or phosphorous. Each class of ligand (e.g., monodentate) may behomogenous or comprise different ligands of the same class.

In some embodiments, the molybdenum precursor comprises onecycloheptatriene ligand. In some embodiments, the molybdenum precursorcomprises two cycloheptatriene ligands. In one or more embodiments, themolybdenum precursor, as shown in FIG. 2A, comprises onecycloheptatriene ligand and three monodentate ligands. In one or moreembodiments, the molybdenum precursor, as shown in FIG. 2B, comprisesone cycloheptatriene ligand, one monodentate ligand and one bidentateligand. In one or more embodiment, the molybdenum precursor, as shown inFIG. 2C, comprises one cycloheptatriene ligand and a tridentate ligand.

In some embodiments, the cycloheptatriene ligand may be substituted withone or more alkyl group. In some embodiments, the cycloheptatrieneligand is substituted with one alkyl group. In some embodiments, thealkyl group contains 1 to 4 carbon atoms. In some embodiments, the alkylgroup is selected from Me-, Et-, iPr-, or tBu-. In some embodiments, thecycloheptatriene ligand is not substituted.

In some embodiments, the monodentate ligand is selected from one or moreof:

In some embodiments, the bidentate ligand is selected from one or moreof:

In some embodiments, the tridentate ligand is selected from one or moreof:

In one or more embodiments, each R may be independently selected fromMe-, Et-, iPr-, and tBu-substituent.

Without intending to be bound by theory, it is thought that each of thenon-cycloheptatriene ligands disclosed herein coordinates to themolybdenum metal center through the carbon, nitrogen or phosphorousatoms of the ligand. Each ligand is expected to impact the volatilityand thermal stability of the metal complex. Accordingly, it is expectedthat through the judicious selection of ligands, a metal precursor withpreferred thermal properties may be produced and used to deposit amolybdenum-containing layer by CVD or ALD.

As used herein, a “substrate surface” refers to any substrate surfaceupon which a layer may be formed. The substrate surface may have one ormore features formed therein, one or more layers formed thereon, andcombinations thereof. The substrate (or substrate surface) may bepretreated prior to the deposition of the molybdenum-containing layer,for example, by polishing, etching, reduction, oxidation, halogenation,hydroxylation, annealing, baking, or the like.

The substrate may be any substrate capable of having material depositedthereon, such as a silicon substrate, a III-V compound substrate, asilicon germanium (SiGe) substrate, an epi-substrate, asilicon-on-insulator (SOI) substrate, a display substrate such as aliquid crystal display (LCD), a plasma display, an electro luminescence(EL) lamp display, a solar array, solar panel, a light emitting diode(LED) substrate, a semiconductor wafer, or the like. In someembodiments, one or more additional layers may be disposed on thesubstrate such that the molybdenum-containing layer may be at leastpartially formed thereon. For example, in some embodiments, a layercomprising a metal, a nitride, an oxide, or the like, or combinationsthereof may be disposed on the substrate and may have the molybdenumcontaining layer formed upon such layer or layers.

At operation 114, the processing chamber is optionally purged to removeunreacted molybdenum precursor, reaction products and by-products. Asused in this manner, the term “processing chamber” also includesportions of a processing chamber adjacent the substrate surface withoutencompassing the complete interior volume of the processing chamber. Forexample, in a sector of a spatially separated processing chamber, theportion of the processing chamber adjacent the substrate surface ispurged of the molybdenum precursor by any suitable technique including,but not limited to, moving the substrate through a gas curtain to aportion or sector of the processing chamber that contains none orsubstantially none of the molybdenum precursor. In one or moreembodiments, purging the processing chamber comprises applying a vacuum.In some embodiments, purging the processing chamber comprises flowing apurge gas over the substrate. In some embodiments, the portion of theprocessing chamber refers to a micro-volume or small volume processstation within a processing chamber. The term “adjacent” referring tothe substrate surface means the physical space next to the surface ofthe substrate which can provide sufficient space for a surface reaction(e.g., precursor adsorption) to occur. In one or more embodiments, thepurge gas is selected from one or more of nitrogen (N₂), helium (He),and argon (Ar).

At operation 116, the substrate (or substrate surface) is exposed to areactant to form one or more of a molybdenum film on the substrate. Thereactant can react with the molybdenum-containing species on thesubstrate surface to form the molybdenum-containing film. In someembodiments, the reactant comprises a reducing agent. In one or moreembodiments, the reducing agent can comprise any reducing agent known ofto one of skill in the art. In other embodiments, the reactant comprisesan oxidizing agent. In one or more embodiments, the oxidizing agent cancomprise any oxidizing agent known to one of skill in the art. Infurther embodiments, the reactant comprises one or more oxidizing agentand a reducing agent.

In specific embodiments, the reactant is selected from one or more of1,1-dimethylhydrazine (DMH), alkyl amine, hydrazine, alkyl hydrazine,allyl hydrazine, hydrogen (H₂), ammonia (NH₃), alcohols, water (H₂O),oxygen (O₂), ozone (O₃), nitrous oxide (N₂O), nitrogen dioxide (NO₂),peroxides, and plasmas thereof. In some embodiments, the alkyl amine isselected from one or more of tert-butyl amine (tBuNH₂), isopropyl amine(iPrNH₂), ethylamine (CH₃CH₂NH₂), diethylamine ((CH₃CH₂)₂NH), or butylamine (BuNH₂). In some embodiments, the reactant comprises one or moreof compounds with the formula R′NH₂, R′₂NH, R′₃N, R′₂SiNH₂, (R′₃Si)₂NH,(R′₃Si)₃N; where each R′ is independently H or an alkyl group having1-12 carbon atoms. In some embodiments, the alkyl amine consistsessentially of one or more of tert-butyl amine (tBuNH₂), isopropyl amine(iPrNH₂), ethylamine (CH₃CH₂NH₂), diethylamine ((CH₃CH₂)₂NH), butylamine (BuNH₂).

At operation 118, the processing chamber is optionally purged afterexposure to the reactant. Purging the processing chamber in operation118 can be the same process or different process than the purge inoperation 114. Purging the processing chamber, portion of the processingchamber, area adjacent the substrate surface, etc., removes unreactedreactant, reaction products and by-products from the area adjacent thesubstrate surface.

At decision 120, the thickness of the deposited film, or number ofcycles of molybdenum-precursor and reactant is considered. If thedeposited film has reached a predetermined thickness or a predeterminednumber of process cycles have been performed, the method 100 moves to anoptional post-processing operation 130. If the thickness of thedeposited film or the number of process cycles has not reached thepredetermined threshold, the method 100 returns to operation 110 toexpose the substrate surface to the molybdenum precursor again inoperation 112, and continuing.

The optional post-processing operation 130 can be, for example, aprocess to modify film properties (e.g., annealing) or a further filmdeposition process (e.g., additional ALD or CVD processes) to growadditional films. In some embodiments, the optional post-processingoperation 130 can be a process that modifies a property of the depositedfilm. In some embodiments, the optional post-processing operation 130comprises annealing the as-deposited film. In some embodiments,annealing is done at temperatures in the range of about 300° C., 400°C., 500° C., 600° C., 700° C., 800° C., 900° C. or 1000° C. Theannealing environment of some embodiments comprises one or more of aninert gas (e.g., molecular nitrogen (N₂), argon (Ar)) or a reducing gas(e.g., molecular hydrogen (H₂) or ammonia (NH₃)) or an oxidant, such as,but not limited to, oxygen (O₂), ozone (O₃), or peroxides. Annealing canbe performed for any suitable length of time. In some embodiments, thefilm is annealed for a predetermined time in the range of about 15seconds to about 90 minutes, or in the range of about 1 minute to about60 minutes. In some embodiments, annealing the as-deposited filmincreases the density, decreases the resistivity and/or increases thepurity of the film. In one or more embodiments, annealing can also withperformed with a gas under plasma. In one or more embodiments, theannealing temperature may be lower with plasma.

In one or more embodiments, the plasma comprises one or more of nitrogen(N₂), argon (Ar), helium (He), hydrogen (H₂), carbon monoxide (CO),carbon dioxide (CO₂) methane (CH₄), and ammonia (NH₃). In someembodiments, the plasma is a remote plasma. In other embodiments, theplasma is a direct plasma.

In one or more embodiments, the plasma may be generated remotely orwithin the processing chamber. In one or more embodiments, the plasma isan inductively coupled plasma (ICP) or a conductively coupled plasma(CCP). Any suitable power can be used depending on, for example, thereactants, or the other process conditions. In some embodiments, theplasma is generated with a plasma power in the range of about 10 W toabout 3000 W. In some embodiments, the plasma is generated with a plasmapower less than or equal to about 3000 W, less than or equal to about2000 W, less than or equal to about 1000 W, less than or equal to about500 W, or less than or equal to about 250 W.

The method 100 can be performed at any suitable temperature dependingon, for example, the molybdenum precursor, reactant or thermal budget ofthe device. In one or more embodiments, the use of high temperatureprocessing may be undesirable for temperature-sensitive substrates, suchas logic devices. In some embodiments, exposure to the molybdenumprecursor (operation 112) and the reactant (operation 116) occur at thesame temperature. In some embodiments, the substrate is maintained at atemperature in a range of about 20° C. to about 400° C., or about 50° C.to about 650° C.

In some embodiments, exposure to the molybdenum precursor (operation112) occurs at a different temperature than the exposure to the reactant(operation 116). In some embodiments, the substrate is maintained at afirst temperature in a range of about 20° C. to about 400° C., or about50° C. to about 650° C., for the exposure to the molybdenum precursor,and at a second temperature in the range of about 20° C. to about 400°C., or about 50° C. to about 650° C., for exposure the reactant.

In the embodiment illustrated in FIG. 1, at deposition operation 110 thesubstrate (or substrate surface) is exposed to the molybdenum precursorand the reactant sequentially. In another, un-illustrated, embodiment,the substrate (or substrate surface) is exposed to the molybdenumprecursor and the reactant simultaneously in a CVD reaction. In a CVDreaction, the substrate (or substrate surface) can be exposed to agaseous mixture of the molybdenum precursor and reactant to deposit amolybdenum-containing film having a predetermined thickness. In the CVDreaction, the molybdenum-containing film can be deposited in oneexposure to the mixed reactive gas, or can be multiple exposures to themixed reactive gas with purges between.

In some embodiments, the molybdenum-containing film formed compriseselemental molybdenum. Stated differently, in some embodiments, themolybdenum-containing film comprises a metal film comprising molybdenum.In some embodiments, the metal film consists essentially of molybdenum.As used in this manner, the term “consists essentially of molybdenum”means that the molybdenum-containing film is greater than or equal toabout 80%, 85%, 90%, 95%, 98%, 99% or 99.5% molybdenum, on an atomicbasis. Measurements of the composition of the molybdenum-containing filmrefer to the bulk portion of the film, excluding interface regions wherediffusion of elements from adjacent films may occur.

In other embodiments, the molybdenum-containing film comprisesmolybdenum oxide (MoO_(x)) with an oxygen content of greater than orequal to about 5%, 7.5%, 10%, 12.5 or 15%, on an atomic basis. In someembodiments, the molybdenum-containing film comprises an oxygen contentin the range of about 2% to about 30%, or in the range of about 3% toabout 25%, or in the range of about 4% to about 20%, on an atomic basis.

In other embodiments, the molybdenum-containing film comprisesmolybdenum carbide (MoC_(x)) with a carbon content of greater than orequal to about 5%, 7.5%, 10%, 12.5 or 15%, on an atomic basis. In someembodiments, the molybdenum-containing film comprises a carbon contentin the range of about 2% to about 30%, or in the range of about 3% toabout 25%, or in the range of about 4% to about 20%, on an atomic basis.

The deposition operation 110 can be repeated to form one or more of amolybdenum oxide film, a molybdenum carbide film, a molybdenum silicidefilm, and a molybdenum nitride film, having a predetermined thickness.In some embodiments, the deposition operation 110 is repeated to provideone or more of a molybdenum oxide film, a molybdenum carbide film, amolybdenum silicide film, and a molybdenum nitride film having athickness in the range of about 0.3 nm to about 100 nm, or in the rangeof about 30 Å to about 3000 Å.

One or more embodiments of the disclosure are directed to methods ofdepositing molybdenum-containing films in high aspect ratio features. Ahigh aspect ratio feature is a trench, via or pillar having aheight:width ratio greater than or equal to about 10, 20, or 50, ormore. In some embodiments, the molybdenum-containing film is depositedconformally on the high aspect ratio feature. As used in this manner, aconformal film has a thickness near the top of the feature that is inthe range of about 80-120% of the thickness at the bottom of thefeature.

Some embodiments of the disclosure are directed to methods for bottom-upgapfill of a feature. A bottom-up gapfill process fills the feature fromthe bottom versus a conformal process which fills the feature from thebottom and sides. In some embodiments, the feature has a first materialat the bottom (e.g., a nitride) and a second material (e.g., an oxide)at the sidewalls. The molybdenum-containing film deposits selectively onthe first material relative to the second material so that themolybdenum film fills the feature in a bottom-up manner.

According to one or more embodiments, the substrate is subjected toprocessing prior to and/or after forming the layer. This processing canbe performed in the same chamber or in one or more separate processingchambers. In some embodiments, the substrate is moved from the firstchamber to a separate, second chamber for further processing. Thesubstrate can be moved directly from the first chamber to the separateprocessing chamber, or it can be moved from the first chamber to one ormore transfer chambers, and then moved to the separate processingchamber. Accordingly, the processing apparatus may comprise multiplechambers in communication with a transfer station. An apparatus of thissort may be referred to as a “cluster tool” or “clustered system,” andthe like.

Generally, a cluster tool is a modular system comprising multiplechambers which perform various functions including substratecenter-finding and orientation, degassing, annealing, deposition and/oretching. According to one or more embodiments, a cluster tool includesat least a first chamber and a central transfer chamber. The centraltransfer chamber may house a robot that can shuttle substrates betweenand among processing chambers and load lock chambers. The transferchamber is typically maintained at a vacuum condition and provides anintermediate stage for shuttling substrates from one chamber to anotherand/or to a load lock chamber positioned at a front end of the clustertool. Two well-known cluster tools which may be adapted for the presentdisclosure are the Centura® and the Endura®, both available from AppliedMaterials, Inc., of Santa Clara, Calif. However, the exact arrangementand combination of chambers may be altered for purposes of performingspecific steps of a process as described herein. Other processingchambers which may be used include, but are not limited to, cyclicallayer deposition (CLD), atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), etch, pre-clean,chemical clean, thermal treatment such as RTP, plasma nitridation,degas, orientation, hydroxylation and other substrate processes. Bycarrying out processes in a chamber on a cluster tool, surfacecontamination of the substrate with atmospheric impurities can beavoided without oxidation prior to depositing a subsequent film.

According to one or more embodiments, the substrate is continuouslyunder vacuum or “load lock” conditions, and is not exposed to ambientair when being moved from one chamber to the next. The transfer chambersare thus under vacuum and are “pumped down” under vacuum pressure. Inertgases may be present in the processing chambers or the transferchambers. In some embodiments, an inert gas is used as a purge gas toremove some or all of the reactants (e.g., reactant). According to oneor more embodiments, a purge gas is injected at the exit of thedeposition chamber to prevent reactants (e.g., reactant) from movingfrom the deposition chamber to the transfer chamber and/or additionalprocessing chamber. Thus, the flow of inert gas forms a curtain at theexit of the chamber.

The substrate can be processed in single substrate deposition chambers,where a single substrate is loaded, processed and unloaded beforeanother substrate is processed. The substrate can also be processed in acontinuous manner, similar to a conveyer system, in which multiplesubstrate are individually loaded into a first part of the chamber, movethrough the chamber and are unloaded from a second part of the chamber.The shape of the chamber and associated conveyer system can form astraight path or curved path. Additionally, the processing chamber maybe a carousel in which multiple substrates are moved about a centralaxis and are exposed to deposition, etch, annealing, cleaning, etc.processes throughout the carousel path.

During processing, the substrate can be heated or cooled. Such heatingor cooling can be accomplished by any suitable means including, but notlimited to, changing the temperature of the substrate support andflowing heated or cooled gases to the substrate surface. In someembodiments, the substrate support includes a heater/cooler which can becontrolled to change the substrate temperature conductively. In one ormore embodiments, the gases (either reactive gases or inert gases) beingemployed are heated or cooled to locally change the substratetemperature. In some embodiments, a heater/cooler is positioned withinthe chamber adjacent the substrate surface to convectively change thesubstrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated (about the substrate axis)continuously or in discrete steps. For example, a substrate may berotated throughout the entire process, or the substrate can be rotatedby a small amount between exposures to different reactive or purgegases. Rotating the substrate during processing (either continuously orin steps) may help produce a more uniform deposition or etch byminimizing the effect of, for example, local variability in gas flowgeometries.

The disclosure is now described with reference to the followingexamples. Before describing several exemplary embodiments of thedisclosure, it is to be understood that the disclosure is not limited tothe details of construction or process steps set forth in the followingdescription. The disclosure is capable of other embodiments and of beingpracticed or being carried out in various ways.

EXAMPLES Example 1: Preparation of Monodentate/TridentateCycloheptatrienyl Stool Complexes

[Mo(toluene)(C₇H₇)]PF₆ was treated with stoichiometric amounts of thedesired monodentate or tridentate ligands in acetonitrile at reflux for8 h. The compounds were isolated by removal of all volatiles undervacuum, or by filtration of the precipitate upon cooling, and thenpurified by recrystallization. The compounds were suspended in THF at 0°C. and NaBH₄ was added in small portions over 1 hour. The reaction wasstirred for a further 1 hour, and then it was evaporated to dryness. Theresidue was dissolved in hexane or ether, filtered and recrystallized.

Example 2: Preparation of Mixed Cycloheptatrienyl Stool Complexes

[Mo(toluene)(C₇H₇)]PF₆ was treated with stoichiometric amounts of thedesired bidentate ligand in acetonitrile at reflux for 8 h. Thecompounds were isolated by removal of all volatiles under vacuum, or byfiltration of the precipitate upon cooling, and then purified byrecrystallization. The intermediate product was treated withstoichiometric amount of the monodentate ligand in acetonitrile atreflux for 8 h and purified as in the previous step. The compounds weresuspended in THF at 0° C. and NaBH₄ was added in small portions over 1hour. The reaction was stirred for a further 1 hour, and then it wasevaporated to dryness. The residue was dissolved in hexane or ether,filtered and recrystallized.

Example 3: Atomic Layer Deposition of Molybdenum Containing Films

General procedure: A silicon substrate is placed in a processingchamber. A molybdenum precursor is flowed into the processing chamber inan atmosphere of nitrogen (N₂) gas over the silicon substrate leaving amolybdenum-precursor terminated surface. Unreacted precursor andbyproducts are then purged out of the chamber. Next, a co-reactant isthen introduced into the chamber that reacts with the surface-boundmolybdenum species. Again, excess coreactant and byproducts are removedfrom the chamber. The resultant material on the substrate is amolybdenum-containing film.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” may encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the materials and methods discussed herein(especially in the context of the following claims) are to be construedto cover both the singular and the plural, unless otherwise indicatedherein or clearly contradicted by context. Recitation of ranges ofvalues herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate the materials and methods and does not pose a limitation onthe scope unless otherwise claimed. No language in the specificationshould be construed as indicating any non-claimed element as essentialto the practice of the disclosed materials and methods.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure. In oneor more embodiments, the particular features, structures, materials, orcharacteristics are combined in any suitable manner.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

1. A metal coordination complex comprising molybdenum(0), at least one cycloheptatriene ligand and optionally one or more neutral ligands, each neutral ligand coordinated by carbon, nitrogen or phosphorous, wherein the metal coordination complex has less than 1% halide and carbonyl groups on an atomic basis and no neutral ligand is coordinated by phosphorus if the ligand is monodentate.
 2. The metal coordination complex of claim 1, wherein the cycloheptatriene ligand is substituted with one or more alkyl group.
 3. The metal coordination complex of claim 1 comprising one or more monodentate ligand.
 4. The metal coordination complex of claim 3, wherein the one or more monodentate ligand is selected from one or more of:

and wherein each R may be independently selected from Me-, Et-, iPr-, and tBu-.
 5. The metal coordination complex of claim 1 comprising a bidentate ligand selected from one or more of:

and wherein each R may be independently selected from Me-, Et-, iPr-, and tBu-.
 6. The metal coordination complex of claim 1 comprising a tridentate ligand selected from one or more of:

and wherein each R may be independently selected from Me-, Et-, iPr-, and tBu-.
 7. A method of depositing a film, the method comprising: exposing a substrate to a molybdenum(0) precursor comprising at least one cycloheptatriene ligand and optionally one or more neutral ligands coordinated by carbon, nitrogen or phosphorous, the precursor having less than 1% halide and carbonyl groups on an atomic basis and no neutral ligand being coordinated by phosphorus if the ligand is monodentate; and exposing the substrate to a reactant to react with the molybdenum(0) precursor to form a molybdenum film on the substrate.
 8. The method of claim 7, wherein the cycloheptatriene ligand is substituted with one or more alkyl group.
 9. The method of claim 7, wherein the molybdenum(0) precursor comprises one or more monodentate ligand.
 10. The method of claim 9, wherein the one or more monodentate ligand is selected from one or more of:

and wherein each R may be independently selected from Me-, Et-, iPr-, and tBu-.
 11. The method of claim 7, wherein the molybdenum(0) precursor comprises a bidentate ligand selected from one or more of:

and wherein each R may be independently selected from Me-, Et-, iPr-, and tBu-.
 12. The method of claim 7, wherein the molybdenum(0) precursor comprises a tridentate ligand selected from one or more of:

and wherein each R may be independently selected from Me-, Et-, iPr-, and tBu-.
 13. The method of claim 7, wherein the reactant comprises one or more of one or more of an oxidizing agent and a reducing agent.
 14. The method of claim 7, wherein the molybdenum film comprises one or more of a molybdenum metal (elemental Mo) film, a molybdenum oxide film, a molybdenum carbide film, a molybdenum silicide film, and a molybdenum nitride film.
 15. The method of claim 7, wherein the substrate is exposed to the molybdenum(0) precursor and the reactant sequentially.
 16. The method of claim 7, wherein the substrate is exposed to the molybdenum(0) precursor and the reactant simultaneously.
 17. The method of claim 7, further comprising purging the substrate of the molybdenum(0) precursor prior to exposing the substrate to the reactant.
 18. The method of claim 17, further comprising purging the substrate of the reactant and repeating the method to provide a molybdenum film having a thickness in a range of from about 0.3 nm to about 100 nm.
 19. A method of depositing a film, the method comprising: forming a molybdenum-containing film in a process cycle comprising sequential exposure of a substrate to a molybdenum(0) precursor, purge gas, reactant, and purge gas, the molybdenum(0) precursor comprising at least one cycloheptatriene ligand and optionally one or more neutral ligands coordinated by carbon, nitrogen or phosphorous the precursor having less than 1% halide and carbonyl groups on an atomic basis and no neutral ligand being coordinated by phosphorus if the ligand is monodentate.
 20. The method of claim 19, wherein the cycloheptatriene ligand is substituted with one or more alkyl group. 